Mechanism for actuating a type bar drive



Sept. 24, 1957 Filed May 15, 1956 R. H. MIMLITCH MECHANISM FOR ACTUA'IING A TYPE BAR DRIVE 2 Sheets-Sheet 1 IN V EN TOR.

ROBERT H. MIMLITCH ATTORNEY Sept. 24, 195 R. H. MIMLITCH 2,807,345

MECHANISM FOR ACTUA'IING A TYPE BAR DRIVE Filed May 15, 1956 2 Sheets-Sheet 2 FIG. 3

9 28 14 1e 21 16b 200 9 26 40 g7 2,807,345 MECHANISM FOR ATUATING A TYPE I BAR DRIVE v Robert H. Mimlitch, Vestal, N. Y., assignor to Internatlonal Business Machines Corporation, New York, N. Y., a corporation of New York Application May 15, 1956, Serial No. 585,094

5. Claims (Cl. 1 97-17) This invention'relates to typewriters and more par 1 United States P C D ticularly to a mechanism for actuating a type bar drive of. a typewriter.

In some typewriters having power driven type bar mechanisms, a cam is moved manually into' engagement with a power roller to initiate a type bar print stroke upon actuation by a key lever. The key touch is dependent upon the force required to rock the cam into engagement with the power roller. Also, the force with which the cam engages the power roller varies with the'operators touch, and this may vary from key to key. Further, when the cam is engaged manually with the power roller, the sudden effect of power operation on the cam and actuating mechanism can be felt at the key caps as a bounce because the key lever is still in contact with the actuating member which is engaged with the cam.

Inthe invention, a tripping mechanism is released and then is spring urged into engagement with a cam to rock the cam into engagement with a power roller. Therefore, the manual load on the key lever is less than it is in those mechanisms in which the manual load includes the rocking of the cam. Since the rocking of the cam'is independent of the operators touch, the touch is substantially uniform from key to key. Since the key lever is not in contact with the tripping mechanism after its actuation, the operator does not feel the bounce at the start of the power stroke.

It is a first object of this invention to provide a new and improved trip mechanism for a power operated type bar drive.

It is'a further object of this invention to provide an improved tripping mechanism between a'key lever and its associated cam mechanism wherein the cam ismoved into engagement with a power roller with substantially the same force independently of the force applied to the key lever. I g

It is another object of this invention to eliminate the finger shock which atypist senses during depression of the key levers. b

It is a still further object of this invention to provide for lighter touch at the key caps to actuate the type bars.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Figure l is a side elevational view of the operating structure for a type bar. 7

Figure 2 is an enlarged side elevational view of a trip member forming part of the operating structure shown in Fig. l.

Figures 3. and 4 are like Fig. 1 but show the parts in different operating positions.

Referring to the drawings it will be noted that there is shown a key lever 10 and associated mechanisms for operating a type bar 11 of a typewriter. For each 2,807,345 Patentedv Sept. 24, 1957 2 character to be typed, a similar mechanism is provided. The key lever 10 is pivotable about a fixed rod 12suitably supported at its ends, and each key lever is provided with a finger button 13 and a restoring spring 14 which urges the key lever 10 to its rest position, as shown in Fig. l. a

The character printing type bar 11 is pivotable about a rod 15 and is operable by a drive cam mechanism which includes a cam lever 16 connected by a link 17 to the type bar 11. Clockwise movement of the cam lever 16 actuates the type bar 11 through the link 17 to engage the type bar 11 with the paper on the usual platen 18. Coupled to the cam lever 16 by a stud 19 is a cam element 20 mounted to pivot about the stud 19. The cam element 20 is provided with a restoring spring 21 which is attached to an ear 16a formed on the cam lever 16 and to an ear 20a on the cam element 20. Normally, the spring 21 holds the cam element 20 away from a power roller 24. The cam element 20 is. provided. with a serrated tread 20b designed to cooperate with the power roller 24 which rotates continually in the counter-clockwise direction. The upper end of the camelement tread 20b clears the power roller 24 with the parts shown in the normal position in Figure l.

The cam element 20 has an elongated tail piece 200 disposed below a trip member 26 which is slidably and pivotally coupled to the cam lever 16 by a stud 27 engaging 'a slot 26a in the trip member. A spring 28 is extended between an ear 261) on the member 26 and an ear 16b on the cam lever 16. In the position shown in Figure 1, the spring 28 holds a shoulder 26c on trip member 26 in engagement with the ear 1612 on the cam lever 16.. As shown more clearly in Fig. 2, the trip member includes a cam portion 26 sloping upwardly from the shoulder 260, a flange 26d, and another flange 26e. When the key lever 10 is depressed, a projection 10a on the key leverimpinges upon the flange 26d and causes the member'26 to pivot counter-clockwise about the stud 27. This results in a sliding of the shoulder 26c downwardly along the ear 16b until the member 26 isfree to move to the left by the urging of the spring 28. At this time, the cam surface 26] engages the ear 16b and causes the trip member to be cammed counter-clockwise as it moves to the left. As the member 26 is cammed about its pivot, the flange 262 on the lower portion of the member 26 engages the elongated tail piece 290 on the cam element 20 and causes the latter to pivot clockwise about the stud 19 until the serrated tread 2% contacts the power roller '24 as shown in Figure 3. Thus, the cam element 20 is operated due to the force of the spring 28 acting upon the member 26; e

' Thereafter, the power roller 24 drives the cam element20 in1a clockwise direction and due to the eccentric shape of the tread 20b, pushesthe stud 19 to-the rightin a short arcuate path, thereby moving the cam lever 16 in a clockwise direction on a pivot 34. This movement of the cam lever 16 causes the type bar 11 to rotate about the rod 15 and engage the platen 1%.

Attached to the cam 20 is a member 38 having its upper end projecting outwardly at a point adjacent to the left hand end of the cam tail portion 200. As the cam is actuated by the power roller, the member 38 engages the flange 26e and slides the member 26 to the right, in opposition to the spring 28. The action of the spring 28 is such that the left hand portion of the member 26 is held continuously in engagement with the ear 16b on the cam lever 16. As shown more clearly in Fig. 4, just before the lower end of the cam tread 20b is disengaged from the power roller, the member 26 reaches a position where its shoulder 26c comes under the ear 16b. At this time, the member 26 is rocked upwardly to a position where the shoulder 26c latches on the ear 16b for holding the member 26 in the position shown in Fig. l. The member 38 is then free of the trip member and can continue its movement in a clockwise direction with the cam 20 until the latter is stopped by engagement of its tail portion 200 with a stationary bar 30. The'cam element 20 is stopped by the bar 30, but the'cam lever 16 continues to move clockwise by its own momentum as well as that of the type bar. A slight movement of the cam lever after the cam is stopped results in a disengagement of the canrfrom the power roller and a returning of the cam to its home position by the spring 21. After engagement of the type bar 11 with the platen 18, the cam lever 16, link 17, and type bar 11 are restored by a spring 40 to the position shown in Fig. 1;

It has been shown that after the key lever trips the release latch 26, the key lever is disconnected from the release latch so that the motion of the type bar driving mechanism will not be transmitted to the key button 13. Further, the only force required of an operator to actuate the type bar driving mechanism is that necessary to move the shoulder 26c on the release latch 26 below the ear 16b on the cam lever 16. The spring 26 provides the energy torock the cam element 20 into engagement with the power roller 24. Thus, light and uniform touch is achieved at the key lever 10.

While there have been shown and described and pointed out the fundamental novel features of the invention, as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A mechanism for actuating a type bar comprising, in combination, a power roller, means including a lever operatively connected to said type bar, means supporting said lever for pivotal movement, a cam pivotally connected to said lever and engageable with said power roller, said cam operating upon engagement with said power roller for pivoting said lever on said supporting means and effecting an actuation of said type bar, means yieldingly urging said cam to a home position free from said power roller, 21 member supported on said lever and movable relative thereto against said cam for rocking the latter into engagement with said power roller, means yieldingly urging said member toward said cam, means engageable with said member for latching the latter in a position free from said cam, and a key lever engageable with said member for releasing the latter from said latching means.

2. A mechanism for actuating a type bar comprising, in combination, a power roller, means including a lever operatively connected to said type bar, means supporting said lever for pivotal movement, a cam pivotally connected to said lever and engageable with said power roller, said cam operating upon engagement with said power roller for pivoting said lever on said supporting means and effecting an actuation of said type bar, means urging said cam to a home position free from said power roller, a latch pivotally and slidably coupled to said lever for rocking the cam into engagement with said power roller, means yieldingly urging said latch toward said cam, means engageable with said latch for restraining the latter in a position free from said cam, and a key lever engageable with said latch for releasing the latter from said restraining means.

3. A mechanism for actuating a type bar comprising, in combination, a power roller, means including a lever operatively connected to said type bar, means supporting said lever for pivotal movement, a cam pivotally connected to said lever and engageable with said power roller, said cam operating upon engagement with said power roller for pivoting said lever on said supporting means and effecting an actuation of said type bar, means yieldingly urging said cam to a home position free from said power roller, a member pivotally and slidably coupled. to said lever for rocking said cam into engagement with said power roller, said member having a restraining portion for holding said member free from said cam, resilient means urging said member toward said cam, and a key lever engageable with said member for releasing said restraining portion of the latter.

4. A mechanism for actuating a type bar comprising, in combination, a power roller, means including a lever operatively connected to said type bar, means supporting said lever for pivotal movement, a cam pivotally connected to said lever and engageable with said power roller, said cam operating upon engagement with said power roller for pivoting said lever on said supporting means and effecting an actuation of said type bar, means yieldingly urging said cam to a home position free from said power roller, a member supported on said lever and movable relative thereto against said cam for rocking the latter into engagement with said power roller, spring means urging said member toward said cam, means engageable with said member for latching the latter in a position free from said cam, a key lever engageable with said member for releasing the latter from said latching means, and means to re-bias said spring means and restore said member free of said cam.

5. A type bar drive mechanism for a typewriter having a power driven roller comprising, in combination, a type bar adapted for movement from a rest position to a print position, a cam lever pivotally coupled to the type bar to manipulate the latter, means supporting said lever for pivotal movement, a cam pivotally mounted on said cam lever and adapted for engagement and disengagement With said power roller, a trip latch pivotally and slidably coupled to said cam lever to pivot said cam element, means normally restraining said trip latch from engagement with said cam element, spring means urging said trip latch effective when the latter is free, and. a key lever adapted to free said trip latch.

No references cited. 

